Foam polystyrene molded materials molded by foam polystyrene have been available as packing materials for packing electronic appliances such as audio apparatus and television receiver and foods such as vegetables, fruits and fish. Because the foam polystyrene molded materials are light in weight and are relatively high in strength, a large amount of foam polystyrene molded materials have been used as cushion materials and packing containers. Although the foam polystyrene molded materials are excellent materials as cushion materials and packing containers as described above, there have occurred various problems when they are wasted after they had been used.
For example, when foam polystyrene is burned up, it is burned up to produce intense heat which as a result damages an incinerator. Moreover, when foam polystyrene is directly buried into soils for disposal, since foam polystyrene cannot be decomposed it does not transform into soil. There arises a problem that foam polystyrene still remains in the soils.
From a viewpoint of protecting environments from being polluted and from a standpoint of how to effectively utilize natural resources, as substitutes for foam polystyrene, there have recently been developed cushion materials and packing containers formed by pulp molding using wasted papers such as newspapers and magazines as main raw materials. As a packing cushion material using such pulp mold, there is proposed a packing pad molded body that is disclosed in FIGS. 2 and 3 of Japanese laid-open patent application No. 11-278551, for example. FIGS. 2 and 3 of the official gazette of the above patent application are referred to as FIGS. 15 and 16.
As shown in FIGS. 15 and 16, this packing pad molded body 1 is used to fix a packed item, for example, a lighting apparatus comprising a lighting apparatus main body 2 and a shade 3 within a packing box 4 and is formed of pulp mold which is integrally formed by mold die. A bending portion 5 having a V-like cross-section is disposed at substantially the central portion of the packing pad molded body 1 such that the bending portion can freely bend inwardly or outwardly and a contact portion 7 comprising a curved portion or contact rib corresponding to the side shape of the shade 3 is provided on one surface 6 of the bending portion 5.
A projection edge portion 10 includes a holding portion 9 that can inwardly bend to hold an end edge 8 of the lighting apparatus main body 2 at its tip end and projects from the contact portion 7 at its portion near the bending portion 5. At the same time, a recess portion 13 for supporting a supporting portion 12 of the lighting apparatus main body 2 at its end edge is provided on the other surface 11, and a holding groove 16 that holds a projection rib edge 14 of the lighting apparatus main body 2 is formed on the other surface. Besides, an engagement portion 16 is formed on the opposing surface of the bending portion 5 in order to engage the opposing surface when they are brought in close contact with each other. Reference numeral 17 denotes a reinforcement rib provided on the other surface 11.
According to this packing pad molded body 1, after the packing pad molded bodies are located at the corners of the packing box 4, the shade 3 is held on the packing pad molded bodies and then held and fixed by the projection edge portion 10 formed on one surface 6. Consequently, within the packing box 4, the shade 3 can be prevented from being rickety and shocks applied to the lighting apparatus within the packing box can be buffered, thereby making it possible to prevent the lighting apparatus from being damaged.
However, in this conventional packing cushion material, there arises a problem that performances needed by this kind of cushion materials cannot be satisfied satisfactorily. Specifically, packing cushion materials are generally examined by a vibration test for testing how much vibrations are buffered and transmitted to the packed article as external input and a drop test for testing how much impact strength are buffered and transmitted to the packed article as external input when the packed article is dropped. Manufacturers of packing cushion materials usually judge the results of the tests according to their own standards and use their products that can satisfy their own standards.
In this case, since a conventional packing cushion material has the structure in which the contact portion 7 is provided on one surface 6 which the side surface of the shade 3 contacts and the reinforcement rib 17 is provided on the other surface 11, in order for the packing cushion material to have sufficient cushion function against the drop test, the contact portion 7 and the reinforcement rib 17 have to increase their rigidity so that the packing cushion material becomes able to sufficiently absorb shocks applied when the packed article is dropped.
When, however, the rigidity of the contact portion 7 and the reinforcement rib 17 is increased, linear protrusion portions of the contact portion 7 and the reinforcement rib 17 support the shade 3 and the lighting apparatus main body 2 and thereby the shade and the lighting apparatus main body come into linear contact with each other. As a result, in the drop test, when the surfaces of the shade 3 and the lighting apparatus main body 2 are coated with paint, there arises a problem that paint tends to easily peel off due to shocks from the contact portion 7 and the reinforcement rib 17.
In the case of the vibration test, when the contact portion 7 and the reinforcement rib 17 are large in rigidity, the contact portion 7 and the reinforcement rib 17 that form the linear contact rub against the surfaces of the shade 3 and the lighting apparatus main body 2, the paints on the shade 3 and the lighting apparatus main body 2 will be damaged easily. Although the receiving surfaces of the contact portion 7 and the reinforcement rib 17 have to increase in space to receive the shade 3 and the lighting apparatus main body 2 with wider areas in order to protect the paint from being damaged, sufficiently large reception surfaces could not be maintained.
Therefore, in order to obtain a sufficiently large cushion capability by using the conventional cushion material made by pulp mold while maintaining their wide areas in contact with the lighting apparatus main body 2 and the shade 3, the thickness of the pulp mold has to increase and the length of the cushion portion has to increase. As a consequence, the cushion material is caused to increase its weight and is also caused to become large in size so that not only the amount of pulp mold to be used increases but also the whole of the packing form becomes large in size inevitably.
In view of the aforementioned problems encountered by the prior art, it is an object of the present invention to provide a packing cushion material which can be molded by pulp mold of a relatively small amount. Although this packing cushion material is small, this packing cushion material can demonstrate a large buffering capability and can protect packed articles softly and can prevent paint from peeling off from the packed article and can prevent the packed article from being damaged.